JP3135379B2 - Image stabilization device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera device such as a video camera having a vibration-proof lens using a variable apex angle prism device capable of arbitrarily changing the traveling direction of a passing light beam.

[0002]

2. Description of the Related Art In recent years, camera apparatuses such as video cameras have been automated, and various functions such as automatic exposure adjusting means and automatic focus adjusting means have been put to practical use.

[0003] As one of these automation functions, blur correction means for reducing harmful blur of a screen caused by various causes has been devised and is being put into practical use.

In particular, in a camera device such as a video camera, a zoom lens is generally used as a photographing lens to be used, and the zoom ratio tends to increase year by year. On the other hand, the miniaturization of camera devices is also remarkable, and with the background of the miniaturization of the imaging screen size, the development of high-density mounting technology, and the development of a small-sized recorder mechanical chassis, small-sized models capable of performing one-handed imaging have appeared.

However, when a small-sized video camera equipped with such a zoom lens is used, harmful blurring of the screen due to camera shake of the photographer occurs, and in order to eliminate this blurring and obtain a stable screen. In addition, various shake preventing means have been proposed. By using these blur prevention means,
Not only do harmful screen shakes caused by such shakes,
Needless to say, when photographing from a ship or a car, a great effect can be obtained even in a situation where harmful camera shake cannot be removed even by using a tripod.

The shake preventing means includes at least a shake detecting means for detecting a shake, and a shake correcting means for performing some kind of correction so that the screen does not shake in accordance with the detected shake information. ing.

As the shake detecting means, for example, an angular accelerometer, an angular velocity meter, an angular displacement meter and the like are known.

Further, as the shake correcting means, a means using a variable apex angle prism by the same applicant or a video camera configured to cut out an area actually used as a screen from the obtained imaged screen information is used. A method of sequentially changing the cutout position to a position at which blur is corrected is known.

As a correction means, a method of removing blur at the stage of an image formed on an image pickup device by using a variable apex angle prism or some other optical means as in the former method is used here as an optical correction method. The method of electronically processing image information including blur, such as the latter, to remove blur is referred to as electronic correction means.

Generally, the optical correction means is capable of correcting a camera shake within an angle defined as a camera shake angle irrespective of the focal length of the lens. Even if the focal length is long,
It is possible to have the blur removal performance which has no practical problem.
However, it has the disadvantage of being large.

On the other hand, the electronic correction means has a constant correction rate on the screen, for example, for the vertical dimension of the screen. Therefore, as the focal length on the telephoto side increases, the performance of blur removal deteriorates. In the case of the electronic type, it is often advantageous for miniaturization.

FIG. 8 is a diagram illustrating the relationship between the focal length and the camera shake angle based on the position of the subject on the screen. In the figure, when the camera is at the position indicated by 22, the optical axis of the lens is 23, which means that the face of the person 21 which is the subject is almost centered. Assume that the camera is rotated by a degree from this state due to camera shake. The camera position at this time is 24
And the optical axis is indicated by 25.

FIGS. 8B and 8C show the screen positions at the camera positions indicated by 22 and 24 in FIG. 8, and FIG. 8B shows the state at the telephoto end of the zoom lens. )
Indicates the state at the wide end. 26 indicates a subject in the screen, 27 and 29 indicate screens at the 22 position, and 28 and 20 indicate screens at the 24 position.

As is apparent from FIG. 9, even if the camera shakes at the same a degree, the longer the focal length of the lens is, the more harmful the camera shake is on the screen. Therefore, especially in the case of a blur removing unit which is combined with a lens having a long focal length at the telephoto end, an optical unit using a variable apex angle prism can be said to be an effective blur correcting unit.

FIG. 9 shows the configuration of the variable apex angle prism. In the figure, 31 and 33 are glass plates, and 37 is a bellows portion made of a material such as polyethylene. A transparent liquid 32 made of, for example, silicon oil or the like is sealed in the interior surrounded by these glass plates and bellows.

In FIG. 9B, two glass plates 31 and 33 are shown.
Are parallel, and in this case, the incident angle and the exit angle of the light beam of the variable apex angle prism are equal. On the other hand, FIG.
In the case of having an angle as shown in FIG.
The ray is bent at an angle, as shown at 36. Therefore, by controlling the angle of the variable apex prism provided in front of the lens so that when the camera is tilted due to camera shake or the like, the spectral line corresponding to the angle is bent.
Blur can be removed.

FIG. 10 shows this state.
In (A), the variable apex angle prism is in a parallel state, and the optical axis captures the head of the subject.
By driving the variable apex angle prism as shown in the figure to bend the light beam against the fluctuation of the degree, the photographing optical axis is still unchanged and the head of the subject can be continuously captured.

FIG. 12 is an exploded perspective view of a variable apex angle prism unit and the like including the variable apex angle prism, an actuator for driving the prism, and an apex angle sensor for detecting an angular state. The actual blur appears in all directions, but in order to cope with this, the front glass surface and the rear glass surface of the variable apex angle prism are configured to be rotatable about a direction shifted by 90 degrees from each other as a rotation axis. . Here, components that perform the same function are denoted by the same reference numerals, but the subscripts a and b indicate components shifted by 90 degrees. Note that some parts on the b side are not shown.

Reference numeral 51 denotes a main body of the variable apex angle prism, which is composed of glass plates 31, 33, bellows 37, and a liquid such as silicon oil inside. The glass plate is integrally attached to the holding frame 38 using an adhesive or the like. The holding frame 38 is rotatable about a rotation shaft 43 between the holding frame 38 and a fixed component (not shown). As described above, the shaft 43a and the shaft 43b
The 90 degree directions are different. The coil 4 is placed on the holding frame 38.
5 are provided integrally, while a fixed portion (not shown) is provided with a magnet 46 and yokes 47 and 48. Therefore, the variable apex angle prism is rotated around the axis 43 by passing a current through the coil. A slit 39 is provided at the tip of an arm portion 40 integrally extending from the holding frame 38, and a light emitting element 4 such as an iRED element provided at a fixed portion is provided.
1 and a light receiving element such as a PSD to constitute a vertex angle sensor for detecting the deviation state of the prism.

FIG. 11 is a block diagram of an image stabilizing control system in which a shake preventing means having the variable apex angle prism as a correcting means is combined with a photographing lens.

In the drawing, reference numeral 51 denotes a variable apex angle prism, 5
Reference numerals 3 and 54 denote apex angle sensors 63 and 64 having the above-described configuration, a detection circuit unit for amplifying the output of the apex angle sensor, 55 a microcomputer, and 56 and 57 a shake detecting means.
The microcomputer 55 controls the angle state of the variable apex angle prism to an angle state detected by the apex angle sensor and an optimum angle state for removing the blur according to the detection results of the shake detecting means 56 and 57. , The current to be supplied to the actuators 58 and 59 is determined.

Note that the main element is composed of two blocks because it is assumed that control in two directions shifted by 90 degrees is performed independently.

Assuming that the refractive index of the variable apex angle prism is n, the apex angle of the prism is σ, and the angle between the incident light beam and the outgoing light beam is δ, the following expression applies within a small range of the apex angle.

Δ = (n−1) σ For example, when n = 1.4, if the variable apex angle prism is tilted by 5 degrees, the light beam will bend twice.

In the above, the blur preventing means using the variable apex angle prism has been described.

[0026]

However, in a correction optical unit for optically correcting image blur, particularly in a vibration-proof optical system using a variable apex prism, when an image is deflected, that is, the apex angle is changed. There is a disadvantage in that decentering distortion occurs when this is done. The description is given below.

FIG. 3 and FIG. 4 are views showing the state of occurrence of eccentric distortion of the variable apex angle prism. FIG. 3 shows the relationship between the on-axis principal ray 16 and the off-axis principal rays 17, 18 when the object side of the two transparent members of the variable apex prism 14 is inclined by σ due to rotation perpendicular to both the optical axis and the paper surface. It shows the situation. It is now assumed that the rotation direction in the paper plane is the pitch direction, and the variable apex angle prism is controlled so that the axial principal ray 16 is δ-deflected (according to the equation described in the section of the prior art) in accordance with the camera shake in the pitch direction. Then, the off-axis principal ray having the angle of view ω in the photographing lens system is incident on the variable apex angle prism at angles of φ1 and φ2, respectively. If the deflection angle (φ−ω) is constant in the entire screen and equal to δ, the image is deflected on the image plane while maintaining its original shape. However, in actuality, φ depends on the angle of view of the photographing lens system.
However, as a result, the deflection angles of the principal rays are different, and the size on the image plane when the same object is photographed is not uniform.
This is distortion due to decentration.

In the case of FIG. 3, (φ2′−ω) is (φ1′−
ω), the image of the subject as shown in FIG. 7A is distorted into a shape as shown in FIG. 7B. Note that the dotted line is an ideal image when there is no distortion.

Therefore, in an image stabilizing optical system for correcting image blur caused by camera shake by deflecting the image in the opposite direction by a variable apex prism, if the above-described eccentric distortion is present, the point at the center of the screen and the axis Since the amount of movement differs at an outside point, even if image blurring is corrected at the center of the screen, an image flow occurs at the periphery. FIG. 7C shows the result of image blur correction of the object shown in FIG. 7A by using a vibration-proof optical system having such an eccentric aberration coefficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a video camera which has high optical performance, and in particular, satisfactorily corrects distortion caused by an anti-vibration optical system.

A feature of the present invention resides in a correction apparatus including a correction unit for optically correcting a blur of an image formed by an objective lens, a conversion unit for converting the optical image into an electric signal, In order to correct the distortion caused by the means, a processing circuit for processing the electric signal is provided.

[0032]

(Embodiment 1) FIG. 1 is a view showing a first embodiment of an anti-vibration system using a variable apex angle prism according to the present invention. 1 is a variable apex angle prism as image blur correction means, 2
Is a photographing lens system, and 3 is a CC for converting an optical image into an electric signal.
An image sensor such as D, 4 is a signal processing circuit for processing a signal from the image sensor, 5 is a shake detecting sensor for detecting shake of a video camera including an optical system, 6 is a yoke of a variable apex prism, and directions of pitches. Sensor for detecting the rotation angle of
Reference numeral 7 denotes a device for driving the variable apex angle prism 1 by the deflection angle calculated by the control circuit 8 based on the information of the sensors 5 and 6, and 9 denotes a zoom position (focal length) of the photographing lens system. Zoom encoder that detects
Is a distortion calculation circuit for calculating a distortion that will be generated based on the output of the rotation angle sensor 6 and the output of the encoder 9, and 11 is a signal processing circuit 4 based on the result of the distortion calculation circuit 10. This is a processing circuit that performs signal processing so that distortion is corrected for the output.

Next, the operation will be described according to the flow shown in FIG. First, after the power is turned on (# 001), it is determined whether or not the camera is in the image stabilization mode by detecting an image stabilization on / off switch (not shown) or the like (# 002). When the mode is not the image stabilization mode, the normal operation is performed as it is, and the process returns to the beginning.
In the anti-vibration mode, after obtaining the shake amount information from the shake detection sensor and the current variable apex angle prism rotation information from the rotation angle sensor 6, (# 003) the variable apex angle prism required for the image stabilization The rotation angle is calculated (# 004). Next, 9
Zoom position of the taking lens obtained from the encoder (# 00)
From 5) and the calculated required variable apex angle rotation angle, the value of the distortion that will occur on the imaging surface is calculated according to an expression described later (# 006). Here, it is determined whether or not to perform the distortion correction based on whether the calculated value of the distortion is within an allowable range (# 007). If it is determined that the correction is not to be performed, a normal blur correction operation is performed ( # 012), return to the beginning. When the calculated distortion is large and exceeds the allowable range, the distortion is corrected.
In that case, normal blur correction is first performed based on the information on the required variable apex angle prism rotation angle calculated previously. Then, the actual rotation angle of the variable apex angle prism at that time is read from the rotation angle sensor 6 (# 009), and the amount of distortion (distortion correction amount) is calculated together with the information of the zoom position encoder 9 (# 010). ), The distortion correction circuit 12 further processes the signal of the signal processing circuit 4 to perform distortion aberration correction.

Next, the relationship between the rotation angle of the variable apex angle prism and the distortion generated on the imaging surface will be described with reference to FIGS. Although the case where the variable apex angle prism is inclined only in the pitch direction has been described with reference to FIG. 3 in the section of the prior art, actually, in each section around the optical axis, both directions of the yoke and the pitch are combined as shown in FIG. I have. It should be noted that σ1 and σ2 can be obtained in relation to the screen aspect ratio depending on how much they are inclined from the yoke axis (pitch axis). In FIG. 4, reference numeral 14 denotes a variable apex prism with a simplified apex angle of σ1 on the object side and σ2 on the image plane side, 15 an imaging lens system, 16 an axial chief ray,
An off-axis principal ray 8 has an angle of view of ω in the taking lens system. If an angle of view through a variable apex prism centered on the δ-deflected on-axis principal ray is defined, the angle of view is ω1 ′ and ω2 ′, which are different between the upper and lower parts of the screen. ω1 ′ and ω2 ′ are the angle of view ω of the photographing lens system and the vertical angles σ1 and σ of the variable vertical angle prism.
2. It is expressed as follows using the refractive index n of the liquid inside the variable apex prism. Assuming that the correction angle δ is δ = (n−1) · (σ1 + σ2), ω1 ′ = φ1 + δ Then, φ1 is obtained by solving the following two equations: sin (ω + σ1) = n · sin (θ1 + σ1) n · sin (θ1) −σ2) = sin (φ1−σ2) ω2 ′ = φ2 + δ Then, φ2 is obtained by solving the following two equations.

Sin (ω−σ1) = n · sin (θ2−σ1) n · sin (θ2 + σ2) = sin (φ2 + σ2) Further, the relationship between the angle of view and the image height, y ′ = f · tanω, is used.

[0036]

[Outside 1] And so on.

Accordingly, the amount of distortion correction is determined by using the angle of view, ie, the image height, the total focal length of the photographing lens system, and the turning angle of the apex angle variable prism as parameters. Therefore, the correction amount is determined by performing calculations at each image height.

In the case of the first embodiment, the correction of the distortion is always performed as long as the distortion exceeds the allowable range. However, in the case of a camera equipped with a known auto-focusing device, the image is blurred during the focusing operation. In the case where convergence occurs, it is desirable not to perform the distortion correction until the focusing state is reached. Therefore, as shown in FIG. 5, information as to whether or not the taking lens is in focus operation is obtained from an auto focus circuit or the like,
During the focusing operation, the distortion is not corrected until the focal point is reached. The flowchart of FIG. 5 is different from the flowchart of FIG. 2 in that step # 020 is added. By doing so, the time required for correcting the distortion can be omitted, so that the accuracy and speed of the autofocus can be increased accordingly.

Further, when calculating the distortion in the first embodiment, the distortion is calculated from the rotation angle of the variable apex prism and the zoom position. Usually, the loop of the flowchart shown in FIG. // 60) seconds, so that it takes too much time for the operation, and an arithmetic unit (microcomputer or the like) for performing the operation may be complicated. Therefore, in the present embodiment, as shown in FIG. 6, the amount of distortion according to the position of the variable apex prism rotation angle and the zoom position on the image plane is stored in the storage device 13 in advance as a table. In the actual operation, the method of calculating the amount of distortion in the flow of FIG. 2 is replaced with the comparison with the stored table from the calculation.

[0040]

As described above, according to the present invention, in the image blur correction device using the variable apex angle prism, the distortion generated by the variable apex angle prism is processed by processing the video signal from the image sensor. By doing so, the problem of distortion due to decentering, which is a disadvantage of the variable apex angle prism, can be effectively solved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an operation flowchart of the first embodiment of the present invention.

FIG. 3 is a diagram illustrating the principle of calculating distortion.

FIG. 4 is a diagram illustrating the principle of calculating distortion;

FIG. 5 is an operation flowchart of the second embodiment of the present invention.

FIG. 6 is a block diagram of a third embodiment of the present invention.

FIG. 7 is a diagram showing distortion generated by a variable apex angle prism;

FIG. 8 is a diagram showing a state in which image blur occurs.

FIG. 9 is a diagram showing an operation of a variable apex angle prism for reducing image blur;

FIG. 10 is a diagram showing the operation of a variable apex angle prism for reducing image blur;

FIG. 11 is a block diagram showing a control circuit for correcting image blur;

FIG. 12 is an exploded perspective view of a variable apex angle prism.

Claims (2)

(57) [Claims] 1. An image blur correction device comprising a correction unit for optically correcting a blur of an optical image formed by an objective lens, wherein the conversion unit converts the optical image into an electric signal, and the correction unit generates the electric image. An image blur correction apparatus, comprising: a processing unit that performs signal processing on the electric signal in order to correct distortion. Wherein said processing means in accordance with the correction amount of the focal distance and the correction means of the objective lens, to the signal processing the electrical signals to vary the amount of correction of distortion
The image blur correction device according to claim 1, wherein: